Surgical tool system with quick release coupling assembly

ABSTRACT

A surgical tool system with a handpiece and a cutting accessory that has inner and outer hubs. The handpiece has a spring biased lock ring that abuts a complementary stop member integral with the accessory outer hub to hold the accessory to the handpiece. An RFID chip is disposed against an inner wall of the accessory outer hub. An elastomeric seal pressed against the inner wall of the accessory outer hub provides environmental protection for the RFID chip. The seal has a rib that extends around the outer perimeter of the proximal end of the outer hub so as to form a seal between the accessory and an adjacent inner wall of the handpiece. Stop tabs extend inwardly from the seal to prevent the drive hub disposed inside the outer hub from falling out.

RELATIONSHIP TO EARLIER-FILED APPLICATION

This application is a continuation-in-part of U.S. patent applicationSer. No. 10/214,937, filed Aug. 8, 2002, the contents of which areincorporated herein by reference.

FIELD OF THE INVENTION

This invention is related generally to a powered surgical tool systemuseful for performing endoscopic surgical procedures and, moreparticularly, to a system with a handpiece and complementary cuttingaccessory that are constructed to allow the rapid coupling anddecoupling of the cutting accessory to the handpiece and that requiresrelatively few components to assemble.

BACKGROUND OF THE INVENTION

Endoscopic surgical procedures are routinely performed in order toaccomplish various surgical tasks. In an endoscopic surgical procedure,small incisions, called portals, are made in the patient. An endoscope,which is a device that allows medical personnel to view the surgicalsite, is inserted in one of the portals. Surgical instruments used toperform specific surgical tasks are inserted into other portals. Thesurgeon views the surgical site through the endoscope to determine howto manipulate the surgical instruments in order to accomplish thesurgical procedure. An advantage of performing endoscopic surgery isthat, since the portions of the body that are cut open are minimized,the portions of the body that need to heal after surgery are likewisereduced. Moreover, during an endoscopic surgical procedure, onlyrelatively small portions of the patient's internal organs and tissueare exposed to the open environment. This minimal opening of thepatient's body lessens the extent to which a patient's organs and tissueare open to infection.

The ability to perform endoscopic surgery is enhanced by the developmentof powered surgical tools especially designed to perform endoscopicsurgical procedures. One such tool, for example, is sold by theApplicant's Assignee under the trademark HUMMER II. This tool is in theform of a cylindrical handpiece designed to be held in the hand of thesurgeon. Internal to the handpiece there is a motor. A front end of thehandpiece is provided with a coupling assembly for releasably holding acutting accessory. The types of cutting accessories that are attached tothese handpieces include edgers, resectors, planers and burrs. Integralwith the motor and coupling assembly is a means for transmitting therotary power developed by the motor to the cutting accessory.

The handpiece also has a suction conduit. This is because, in anendoscopic surgical procedure, irrigating fluid is introduced into thesurgical site. This fluid serves as transport media for removing tissueand debris from the surgical site. In order to remove the irrigatingfluid, and the material in the fluid, a suction path is provided throughthe cutting accessory and the handpiece. A suction pump is connected tothe handpiece to provide the suction force needed for drawing the fluidand material away from the surgical site. In order to control thesuction flow through the cutting accessory and the handpiece, thehandpiece is provided with a manually operated valve. Thus, with asingle handpiece, a surgeon both manipulates the cutting accessory andcontrols the suction of material away from the surgical site.

While current endoscopic surgical tool systems have proven useful, thereare some disadvantages associated with their construction. Some of thesedisadvantages are associated with the coupling assemblies integral withthe handpieces. For example, many coupling assemblies are provided withrelease levers that a surgeon or an assistant pivots to place thecoupling assembly in a release state wherein a cutting accessory can beremoved from the handpiece. Some coupling assemblies are provided withcoupling assemblies that not only must be placed in the release state toremove a cutting accessory, but must also be placed in the release statein order to couple a cutting accessory to the handpiece. Requiringmedical personnel to perform this step can add to the overall time ittakes to remove and replace cutting accessories.

Moreover, often a coupling assembly comprises numerous components.Providing these components and arranging them together to form afunctional coupling assembly adds to the overall cost of providing thehandpiece to which the coupling assembly is attached. Anotherdisadvantage associated with providing a coupling assembly that hasnumerous components is that, as with any system, the more componentsthat are provided increases the possibility that, due to the failure ofone component, the whole assembly will malfunction. This is especiallytrue when a system is provided with a large number of moving components.

Also, as discussed in application Ser. No. 10/214,937, the Applicationfrom which this application claims priority and which is incorporatedherein by reference, recently there has been an interest in providingsurgical tool systems that allow data to be inductively transferredbetween the handpiece and the complementary cutting accessory. Thissystem requires the placement of a coil in the distal end, the frontend, of the handpiece so that there can be inductive signal transferbetween it and a complementary coil in the adjacent proximal end of theassociated cutting accessory. This means that, not only must the frontend of the handpiece contain the components forming a coupling assembly,it must also have a space in which a coil can be housed. Given thecomponents that comprise some coupling assemblies, the only way bothgoals can be accomplished is to increase the overall length of thehandpiece. This may require lengthening of the proximal end of thecomplementary cutting accessory, the end fitted in the handpiece. Thishandpiece lengthening can increase the overall size and weight of thehandpiece. These increases run contrary to one goal of modern surgicaltool design. This goal being that, to facilitate ease of use of asurgical tool, its size should be kept as small as possible and itsweight as low as possible.

SUMMARY OF THE INVENTION

This invention relates generally to a new powered surgical tool systemthat can be used to perform surgical procedures such as endoscopicsurgical procedures. The system of this invention includes a handpiecewith a coupling assembly that is relatively easy to assemble. Thecoupling assembly of this invention also has an easy to operate releasebutton and is further designed so that it does not have to be placed ina release state in order to fit a cutting accessory to the associatedhandpiece. The coupling assembly of this invention includes a collet inwhich it is possible to fit a coil in order to facilitate the inductivesignal transfer of data between the handpiece and the complementarycutting accessory.

The system of this invention has a cutting accessory with an outer huband an inner drive hub. The outer hub has an ear with a relativelysimple geometry that forms the locking member for holding the accessoryto a handpiece. An RFID tag is disposed in the hub. A seal is locatedaround the RFID tag to protect the tag from the ambient environment. Theseal is provided with stop tabs. Collectively, the stop tabs and a headsection of the drive tube cooperate to hold the drive hub in the outerhub. The seal also is formed with ribs that are located outside theproximal end of the outer hub. The ribs provide a seal between thecutting accessory and the adjacent inner wall to which the cuttingaccessory is mounted.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is pointed out with particularity in the claims. The aboveand further advantages may be better understood by reference to thefollowing description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a perspective view of an endoscopic surgical handpiece of thisinvention that depicts a complementary cutting accessory secured to thehandpiece;

FIG. 2 is a cross sectional view of the distal end of the handpiece towhich a cutting accessory is attached;

FIG. 3 is a cross sectional view of the components forming the couplingassembly of this invention;

FIG. 4 is an exploded view of the coupling assembly;

FIG. 5 is a longitudinal cross sectional view of the coupling assemblycollet;

FIG. 6 is a lateral cross sectional view of the coupling assembly collettaken along line 6—6 of FIG. 5;

FIG. 7 is a perspective view of the locking ring and release button;

FIG. 8 is a cross sectional view of the locking ring and release button;

FIG. 9 is a plan view of the hub of the cutting accessory of thisinvention;

FIG. 10 is a perspective view of the coil seal of the cutting accessory;

FIG. 11 is a cross-sectional view of the coil seal of the cuttingaccessory; and

FIG. 12 is a perspective view of the cutting accessory tag assembly.

DETAILED DESCRIPTION

The surgical tool system 18 of this invention, as seen in FIGS. 1 and 2,includes an endoscopic handpiece 20, sometimes called a surgical tool. Acomplementary cutting accessory 22 is attached to the handpiece 20. Thehandpiece 20 includes a generally cylindrical, elongated housing 24. Thedistal end of the housing 24 is formed with a bore 26 for receiving theproximal end of the cutting accessory 22. (Throughout this document,“distal” is understood to be away from the face of the surgeon holdingthe handpiece 20; “proximal” is understood to mean towards the face ofthe surgeon.) A motor 28, depicted in phantom, is disposed inside thehousing. A rotating output shaft 30, which is connected to the motor 28for actuation by the motor, is disposed inside bore 26. A couplingassembly 32 is mounted to the front end of the housing 24 for removablyholding the cutting accessory 22 to the handpiece 20.

The cutting accessory 22 includes a drive hub 34 that releasably engagesthe output shaft 30. For the purposes of this invention, the exactgeometry of the output shaft 30 and drive hub 34 that facilitate thereleasable engagement of these components is not relevant. By way ofexample though, in the depicted version of the invention, a drive pin 36extends through the distal end of motor output shaft 30. The drive hub34 is formed to have a slot 37 that extends forward from the proximalend of the hub. When the cutting accessory 22 is fitting in handpiecebore 26, the shaft drive pin 36 seats in the drive hub slot 37. Theseating of the drive pin 36 in the drive hub slot 37 causes the drivepin to impart the rotation moment of the output shaft to the drive hub.

The cutting accessory 22 includes a static outer hub 38 which surroundsthe drive hub 34 that is held in housing bore 26 by the couplingassembly 32. A tubular drive shaft 40 is integrally attached to thedrive hub 34 and extends forward, distally from the drive hub 34 throughthe outer hub 38 and forward from the handpiece 20. A cutting head, suchas a burr or open window shaver, shaver illustrated, is attached to orintegrally formed with the distal end of the drive shaft 40. Atubular-shaped outer shell 42, sometimes called the outer housing,extends forward from the outer hub 38 and surrounds the drive shaft 40.The extent to which the distal end of the outer shell 42 surrounds thedrive shaft 40 cutting head is a function of the design of theparticular cutting accessory 22. It should be further understood thatthe distal end of the drive shaft 40 is provided with an opening 41through which suction is drawn from the surgical site.

When the surgical tool system 20 of this invention is employed toperform a surgical procedure, irrigating fluid is introduced into thesite through the distal end of the cutting accessory. This fluid may beflowed to the site through the annular space between the drive shaft 40and the inner wall of outer shell 42. Alternatively, the fluid isintroduced through a separate cannula that opens into the surgical site.Suction is drawn through the handpiece 20 and drive shaft of theaccessory 22 to remove irrigating fluid and the material entrained inthe irrigating fluid.

Handpiece housing 24 is formed with an elongated bore 50 that extendsaxially through the housing. The distal end of bore 50 is locatedrearwardly from the proximal portion of the bore 26. While not seen inthe drawings, it should be understood that bore 50 is the space in whichthe handpiece motor 28 is seated. The distal end of housing 24 is formedto have a ring shaped head 52 that defines a first counterbore 54 thatis coaxial with bore 50. Immediately proximal to head 52, housing 24 hasa second counterbore 55 also coaxial with bore 50. Second counterbore55, which has a diameter between that of bore 50 and the firstcounterbore 54, is a transition bore between bore 50 and the firstcounterbore 54. A suction bore 56 branches off of bore 50. Suction isdrawn through the cutting accessory drive shaft 40 through the suctionbore 56. Partially seen in FIG. 2 is a valve bore 58 that intersects thesuction bore 56. A valve (not illustrated), is disposed in the valvebore 58 for regulating the suction flow through the cutting accessory 22and the handpiece 20.

The coupling assembly, now described primarily by reference to FIGS. 2,3 and 4, is secured to the distal end of the handpiece housing 24.Specifically, the coupling assembly includes a generally ring shapedcollet 60 that is secured to the housing 24. Collet 60 is the portion ofthe handpiece 20 that defines bore 26. A locking ring 62 is movablydisposed in the collet 60. A cover plate 64 is fitted over the collet 60and locking ring 62 so as to hold the locking ring to the collet. A wavespring 66 seated between the collet 60 and the locking ring 62 biasesthe locking ring into a locked state in which the ring holds the cuttingaccessory outer hub 38 in handpiece bore 26.

The collet 60, is formed of a plastic able to withstand the rigors ofsteam sterilization, such as a polyphenylsulfone plastic, one suchplastic being sold under the trademark RADEL by Amoco Chemicals/BritishPetroleum. In some versions of the invention, the plastic forming thecollet 60 is 15% to 30% glass filled. The collet 60, as seen in detailin FIGS. 4–6, includes a sleeve-shaped base 70. Extending distally frombase 70, the collet 60 has a head 72 that has an outer diameter greaterthan the outer diameter of the base 70. Bore 26 extends axially throughcollet 60, from the distal end of head 72 to the proximal end of base70. Collet 60 is further formed so that head 72, has an arcuate-shapedrecessed section 74 that surrounds between 190° and 250° of the outercircumference of the collet. In more preferred versions of theinvention, recessed section 74 surrounds between 230° and 240° of theouter circumference of head 72. Within recessed section 74, collet head72 is further shaped to have a laterally extending slot 76 that opensinto bore 26. Immediately proximal to slot 76, the collet head 72 isshaped so as to have two small flat surfaces 78 that angle away from anapex that is parallel with the longitudinal axis of the collet 60.Collet head 72 is further formed so that within each flat surface 78there is a groove 80 with a flat base surface recessed from theassociated flat surface 78.

Collet 60 is formed so that within head 72 and the adjacent distalsection of base 70 there is an inner wall 82 with a constant diametercircular cross-sectional profile that defines the distal portion of bore26. Within head 72, collet 60 is further formed so that there is anarcuate groove 84 that extends inwardly of wall 82, away from the centeraxis of the collet. Groove 84 is diametrically opposite the arcuatesection of collet head 72 inscribed by slot 76. Collet 60 is furthershaped to have two diametrically opposed slots 86 that extend proximallyaway from the distal end opening of head 72 and terminate immediatelyforward of the proximal end of the head. Slots 86 are diametricallyopposed from each other. A first one of the slots 86 intersects slot 76;the opposed slot 86 intersects groove 84. It should be understood thatgroove 84 has a depth greater than that of the intersecting slot 86. Aswill be understood hereinafter, the greater depth of groove 84 isdesigned to provide space so that the adjacent section of the lockingring 62 can extend into the portion of groove 84 located below theintersecting slot 86.

Collet 60 is further formed to have a skirt 88 that extends proximallyfrom the proximal end of head 72 and circumferentially surrounds theadjacent distal end of base 70. More particularly, it will be noted thatskirt 88 is spaced away from the outer surface of the portion of thebase surrounded by the skirt so as to define an annular space 90 betweenthese two components of the collet 60. Skirt 88 is shaped so that aroundits outer surface there are two spaced apart, circumferentiallyextending grooves 91.

The collet 60 is shaped so that the portion of base 70 that extendsrearwardly from head 72 has both a generally constant outer diameter andwall thickness. The proximal end of the base 70 has an annular tailsection 92 that is stepped inwardly from the more distal portions of thebase. More particularly, there is a stepped surface 94 along the outsideof the base between the distal portions and tail section 92 that has acurved cross-sectional profile. Also, collet 60 is shaped so that insidebase 70, immediately distal to tail section 92, there is an inner wallsection 96, immediately distal to wall 82, with an inwardly curvedprofile.

Locking ring 62 is formed of a sterilizable metal, such as stainlesssteel. The locking ring 62, now described by reference to FIGS. 4, 7 and8, is shaped to define a center opening 102 with a shape that is oval.Locking ring 62 is further formed to have a lip 104 that projects intoopening 102 from one of the curved ends of the ring. Lip 104 providesthe end of the ring 62 with which it is integral a taper such that theoverall wall thickness of the ring increases along a line that extendsproximally away from the distal-facing side of the ring.

A release button 106 is integrally formed with the locking ring 62 so asto be located on the side of the ring opposite the side with which lip104 is integral. More specifically, release button 106 both subtends theend of the ring to which the button is mounted and extends proximallyaway from the ring. A slot 108 is formed in the portion of the ring 62to which release button 106 is attached. Slot 108 opens into centeropening 102 and has the same cross-sectional profile as the slots 86formed in collet 60.

As part of the assembly of handpiece 20 of this invention, collet 60 isattached to handpiece housing 24. Specifically, the collet base 60 seatsin the second counterbore 55, as seen in FIG. 2. Prior to the attachmentof the collet to the handpiece housing 24, a coil 110 is seated inannular space 90. The coil, which may be a wire wrap or a conductivetrace formed on a flexible substrate, is the coil used to facilitateinductive signal transfer to/from a radio frequency identificationdevice (RFID) chip 170 disposed in the accessory outer hub 38 (FIG. 12).Coil 110 is connected to downline signal processing components throughconductors 114 that extend through a longitudinally extending bore 113formed in the handpiece housing 24.

An O-ring 116 extends around the collet base tail section 92. O-ring 116abuts the stepped surface of housing 24 that defines the transition frombore 50 to second counterbore 55. More particularly, the stepped surfaceof housing 24 is formed to define a groove 118 with an arcuate profilein which O-ring 116 seats. The inner portion of O-ring 116 is seatedagainst the curved collet step surface 94.

Collet 60 is secured to handpiece housing 24, in part, by an adhesivecapable of withstanding the rigors of sterilization, such as a siliconeadhesive. The adhesive is placed between the opposed surface of housinghead 52 and collet skirt 88. A fraction of the adhesive collects in thegrooves 91 that extend around the outer surface of skirt 88. Upon thecuring of the adhesive in the grooves, the adhesive forms two O-rings119 between the housing 24 and the collet 60. The O-rings 119 preventfluid flow from the ambient environment moving through thehandpiece-collet interface.

Removable set screws, not illustrated, further hold the collet 60 to thedistal end of the housing 24. These set screws extend through threadedbores 119 formed in the distal end of the handpiece housing 24, (onebore shown in FIG. 1). The ends of the set screws set in recesses 120formed in the outer surface of collet base 70, (one recess shown in FIG.4).

Locking ring 62 is slip-fitted in collet slot 76. More particularly, thelocking ring 62 is attached to the collet 60 so that the end of the ringwith which lip 104 is integral seats in groove 84. When the locking ring62 is fitted to the collet 60, the release button extends rearwardly,over flat surfaces 78 and the adjacent portion of the recessed section74.

The wave spring 66 is disposed between the collet head 72 and therelease button 106. Specifically, each end of the wave spring 66 isseated in a separate one of the grooves 80 formed in the collet head 72.The topmost crest portion of the wave spring is fitted against arecessed surface 122 formed in the release button 106 immediatelyproximal to locking ring 62.

Cover plate 64 is snap-secured in the recess 74 formed in the collethead. The cover plate 64 has an arcuate shape corresponding to that ofthe collet recess 74. There is an opening 124 in the center of the placethrough which release button 106 extends. In the illustrated version ofthe invention, the cover plate 64 has a center section 126 with greaterwall thickness than that of the surrounding ends. Opening 124 is formedin the center section 126.

The static outer hub 38, which is formed of rigid plastic, is nowdescribed by reference to FIGS. 9, 10 and 11. The outer hub 38 isconstructed to have a sleeve-shaped base 130. The base 130, it will beobserved, is formed with two diametrically opposed, generallyrectangularly shaped openings 132. Extending forward from base 130 andformed integrally therewith is a substantially solid head 133. Whilehead 133 is substantially solid, the outer hub 38 is formed so that abore 134 extends axially through the head. Outer shell 42 is mounted inbore 134 in any conventional manner to extend forward from head 133. Inthe depicted version of the invention, the outer surface of hub head 133is provided with threading, not identified. The threading is provided tofacilitate the releasable screw securement of the cutting accessory 22to a cannula fitted in the portal formed in the patient and directedtowards the surgical site.

Outer hub 38 is further formed to have two diametrically opposed ears135 that are integrally formed with, and extend outwardly from, the base130. Each ear 135 is formed so as to have a relatively shortproximally-directed face 136 that extends laterally away from thelongitudinal axis of the hub 38. Distal to face 136, each ear 135 has aparallel distally directed face 138. A side surface 137 extends betweenthe opposed faces 136 and 138 of ear 135. Each ear is formed such thatthe side surface 137 has a rise or taper at least adjacent theproximally-directed faces 136 such that overall thickness of the ear 135increases moving away from face 136. In some versions of the invention,the ears 135 are formed so that side surfaces 137 have a profile that,extending from the proximally-directed faces 136 is curved or arcuate.

In the depicted version of the invention, laterally extending grooves131 are formed in the distal end of the outer hub base 130. The grooves131 extend circumferentially around the base. Two longitudinally offset,parallel sets of grooves 131 are shown. Each set of grooves consists ofa set of spaced apart grooves. Grooves 131 are provided to reduce theoverall amount of material required to provide the outer hub 38 and tofacilitate the injection molding of the outer hub.

A generally tube-shaped coil seal 139 is disposed in hub base 130. Coilseal 139 is formed from flexible sterilizable material. In one versionof the invention, coil seal 139 is formed from a silicon rubber that has55 Shore A durometer hardness. The coil seal 139 is shaped to have afirst end section, distal end section 140, that has a constant outerdiameter and inner diameter. Extending proximally from the distal endsection 140, the coil seal 139 has a main section 142. Main section 142has the same inner diameter as distal end section 140 and a narrowerouter diameter. The coil seal 139 is further formed to define agenerally rectangular recess 144 in the outer surface of main section142. Located proximal to main section 142, the coil seal 139 has asecond end section, proximal end section 146. The inner and outerdiameters of proximal end section 146 are the same as those of thedistal end section 140. The proximal end section 146 of the coil seal139 is further formed to have two diametrically opposed lock tabs 148.Each lock tab 148 extends radially outwardly from the outer surface ofthe locking section 146. The locking section also has two diametricallyopposed stop tabs 150 that extend inwardly from the inner wall of thelock section. In the depicted version of the invention, each stop tab150 is radially aligned with a separate one of the lock tabs 148.

Coil seal 139 is further formed to have a tail section 152 that extendsrearwardly from the locking section and that forms the proximal end ofthe seal. The tail section 152 is formed to define two annular spacedapart ribs 154 and 156 that extend circumferentially around coil seal139. Both ribs 154 and 156 extend beyond the outer diameter of the seallocking section 146. In the depicted version of the invention, thediameter of the circle subtended by the more proximal of the two ribs,rib 156, is less than the diameter subtended by the other rib, rib 154.Tail section 152 is further formed to have an inner wall that isoutwardly flared.

When a cutting accessory 22 of this version of the invention isassembled, an RFID chip 170, seen in FIG. 12, is seated in seal recess144. A coil 172 connected to the chip 170 is disposed over the reduceddiameter outer surface of seal main section 142. In the version of theinvention depicted in FIG. 12, the. chip 170 is mounted on a small flexcircuit 171; the coil 172 is a conductive trace formed on the flexcircuit 171. After manufacture of the flex circuit 171, the flexcircuit, with the chip 170 mounted thereon, is wrapped in cylinder overseal main section 142 so that the chip seats in recess 144.

The RFID chip-coil-and-seal assembly is fitted in hub base 130.Consequently, both the RFID chip 170 and coil 172 are disposed betweenthe inner wall of the hub base and the outer surface of coil seal 139.Owing to the relative dimensions of outer hub 38 and coil seal 139, theouter surfaces of the seal's distal end and proximal end sections 140and 146, respectively, press against the inner wall of the hub base 130.This contact forms a seal around chip 170 and coil 172. Thus, in mostpreferred versions of the invention, there is no need to employ anadhesive or other chemical to provide a moisture barrier around the chip170 and coil 172.

As part of the insertion of the coil seal 139 into the outer hub 38,lock tabs 148 are seated in hub base openings 132. The seating of thelock tabs 148 in openings 132 holds the coil seal 139 to the outer hub38. When the coil seal 139 is so attached to outer hub 38, tail sectionribs 154 and 156 are located proximal to the proximal end opening of thehub.

As described above, the drive hub 34, now described by reference to FIG.2, transfers the rotary motion of the handpiece output shaft 30 to thecutting accessory drive shaft 40. The drive hub has a stem 173 that isthe proximal end portion of the drive hub. Stem 173 is the portion ofthe drive hub 34 that is formed with the geometric features thatfacilitate the coupling of the hub to the motor output shaft 30. Locatedwithin the base of the bore within stem 173 there is a coil spring 169with a conical profile.

Extending forward from stem 173, the drive hub 34 has a neck 174 thatextends into the proximal end opening of the outer hub 38. In thedepicted version of the invention, neck 174 has a diameter less thanthat of stem 173. A head 176 located forward of the neck 174 forms thedistal end of the drive hub 34. Head 176, it will be observed, has alarger diameter than the adjacent neck 174. More specifically, the drivehub 34 is formed so that neck 174 has a diameter less than that of theopen section defined by the inner surfaces of coil seal stop tabs 150.In contrast, drive hub head 176 has a diameter that is slightly greaterthan the opening defined by the coil seal stop tabs 150. For example, inone version of the invention, the neck 174 of the drive hub 34 has anouter diameter of 0.31 inches and head 176 has a diameter of 0.344inches. In this version of the invention, the open section of the boredefined by the coil seal tabs 150 once the coil seal 139 is seated inthe outer hub 38 and slightly compressed is between 0.33 and 0.34inches.

A bore 177 extends from the distally directed front face of the drivehub head 176, through head 176 and partially through neck 174. Theproximal end of the drive shaft 40 is secured in the distal portion ofbore 177 by any conventional means. The drive hub 34 is further formedto have a suction port 180 on one side of the neck 174 that curves into,and is in fluid communication with, the proximal end of bore 177.Suction port 180 is the opening in the drive hub 34 through whichsuction is drawn.

The cutting accessory 22 is assembled by inserting the drive shaft 40through the outer hub 38 and into the outer shell 42. When the cuttingaccessory 22 is so assembled, the drive hub and drive shaft subassemblyare moved past coil seal 139 in hub bore 134. Owing to the dimensioningof the components, the drive coupler head 176 abuts the coil seal stoptabs 150. Owing to the compressibility of the material from which thecoil seal 139 is formed, a small amount of force compresses the stoptabs 150 to allow the complete insertion of the drive coupler androtating shaft. After assembly, if the cutting accessory 22 is heldvertically, the drive hub head 176 will drop so as to abut stop tabs150. Thus, the stop tabs 150 prevent gravity, without any additionalforce, from causing the drive hub 34 and drive shaft 40 to drop out ofouter hub 38.

In the depicted version of the invention, a washer 183 is shownsurrounding the portion of the drive shaft 40 located immediatelyforward of the drive hub 34. Washer 183 is thus sandwiched between thedistally-directed face of the drive hub 34, and the adjacent proximallydirected recessed face of the outer hub 38. Washer 183 is provided withsome cutting accessories 22, such as burs, as both a spacer and toreduce the friction contact between the drive and outer hubs 34 and 38,respectively.

The cutting accessory 22 is secured to the handpiece 20 by inserting thedrive and outer hubs 34 and 38, respectively, into the open end ofcollet bore 73. The outer hub ears 135 are inserted in collet slots 86.As the outer hub 34 is seated in opening 26, the arcuate side surface137 of the ear 135 adjacent the locking ring lip 104 presses against thelip. Owing to the complementary tapers of lip 104 and the adjacent ear135, the movement overcomes the force of wave spring 66 that urges thatlip into the slot 86. Thus, the lip 104, and the adjoining arcuatesection of the locking ring 62 are pressed into collet groove 84 so thatthe ear 135 can pass over the lip.

Once the outer hub ear 135 passes over the locking ring lip 104, thewave spring 66 urges the lip back into the position in which the lip iswithin the portion of groove 84 that intersects the contiguous slot 86.When the locking ring 62 is so seated, lip 104 abuts thedistally-directed face 138 of the ear 135 to hold the outer hub 38 andthe whole of the cutting accessory 22 to the handpiece 20. When thecoupling assembly 32 is in this state, the assembly is considered in thelocked state.

While not part of this invention, it should be understood that, owing tothe geometry of the proximal end of the drive hub 34, the seating of thecutting accessory 22 in opening 26 causes the drive hub 34 to engage themotor output shaft 30. When the drive hub 34 is so seated, the narrowdiameter end of spring 169 presses against the distal facing face of themotor output shaft 37. Spring 169 thus pushes the drive hub 34 forward.

When the cutting accessory 22 is fitted in the handpiece opening 26,ribs 154 and 156 abut the tapered inner wall section 96 of collet base70. Ribs 154 and 156 thus function as a seal that prevents leakage fromthe suction channel to the outside environment.

As a result of the coupling of the cutting accessory 22 to the handpiece20, accessory coil 172 is disposed in the space surrounded by handpiececoil 110. The coils 110 and 172 are thus in close enough proximity toeach other so that there is inductive coupling of signals between thecoils.

During the course of a surgical procedure, a surgeon may want to replacethe cutting accessory 22 attached to the handpiece 20 with a differentcutting accessory. The installed cutting accessory is removed by thedownward depression of the release button 106. This action causes a likedownward movement of the locking ring 62 so that lip 104 retracts intothe portion of groove 84 below the contiguous slot 86. As a result ofthis motion, lip 104 moves clear of the adjacent outer hub ear 135. Oncethe locking ring 62 is so positioned, the coupling assembly 32 isreferred to as being in the release state. The transition of thecoupling assembly 32 to the release state allows the spring 169, whichis previously compressed, to expand. Since the distal end of the spring169 is disposed against the drive hub 34, the spring pushes the drivehub 34, and therefore the outer hub 38, a short distance forward of theopen end of bore 26. Consequently, it becomes a simple task to manuallypull the cutting accessory 22 from the handpiece 20.

Once the cutting accessory 22 is extracted from the bore 26 so that theouter hub ear 135 clears the locking ring 62, the pressure on thehandpiece can be released without adversely effecting the removal of thecutting accessory. The replacement cutting accessory 22 is then insertedinto the handpiece 20. As with the insertion of the first cuttingaccessory 22, there is no need for the medical personnel to depress therelease button 106 in order to secure the new accessory to the handpiece20.

The coupling assembly 32 of this invention is constructed out of just afew components. Only two of the components, the locking ring 62 and thewave spring 66, move. Thus, given the relatively small number ofcomponents incorporated into this coupling assembly, and the fact thatonly two of the components move, it is relatively economic both toprovide the parts of this assembly and to put them together tomanufacture the completed assembly.

The coupling assembly 32 of this invention is further constructed sothat it does not have to be placed into the release mode in order forthe assembly to lock a cutting accessory 22 to the handpiece 20 withwhich the assembly is integral. Collectively, the handpiece 20 andcomplementary cutting accessory 22 are arranged so that either of theouter hub ears 135 can seat in either of the collet slots 86. Thus,during the process of fitting the cutting accessory 22 to the handpiece20, the accessory does not need to be rotated more than 180° before theaccessory is properly aligned to be inserted into the handpiece opening26. Both of these features of the invention make it possible forsurgical personnel to rapidly fit a cutting accessory to the handpiecewith relatively little manipulation or concentration.

Also, the collet 60 of the described version of the invention is formedfrom plastic. Thus, since the collet 60 is non-metallic, the collet canreadily serve as a housing for coil 110 and not adversely affect theinductive signal transfer between coils 110 and 112. Also, the materialfrom which the collet 60 is formed is lighter in weight than thealuminum from which the handpiece housing 24 is formed. Thus, byproviding a plastic collet, the overall weight of the coupling assembly,and the handpiece 20 to which it is installed, is minimized. Theminimization of handpiece weight serves to lessen the fatigue to which asurgeon is exposed as a result of having to hold and manipulate thehandpiece for an extended period of time.

Still another feature of this invention is that the inner wall section96 of collet 60, the surface of the collet against which ribs 154 and156 abut is curved. Consequently, as soon as there is forward movementof the drive hub 34 out of bore 26, the surface contact between the ribs154 and 156 and the collet 60 is broken. The breaking of this contactmeans causes a like break in the friction bond that would otherwise holdthe ribs 154 and 156 to the collet. The breaking of this bond means thatthe kinetic force released by the continued expansion of spring 169 isnot applied to overcoming friction bond. Instead this spring forceserves to urge the hubs 34 and 38 of bore 26.

Another feature of the coupling assembly 32 of this invention is that ithouses coil 110. Thus, in a relatively short overall section of thehandpiece, in a section usually less than 1.7 inches or less in lengthand, more particularly, 1.4 or less inches in length, the handpiece ofthis invention has both a coupling assembly and a coil that is employedto read and write data into a RFID chip 170 fitted in the cuttingaccessory 22.

Moreover, the locking members that are integral with the cuttingaccessory 22 of this invention, ears 135, are, from a manufacturingstandpoint, relatively easy to provide. It is a relatively simple taskto form the ears 135 during the molding of the outer hub 38.

Coil seal 139 of the cutting accessory 22 performs a number of differentfunctions. Specifically, the seal serves as one of the components thatprotects the RFID chip 170 and coil 172 from the ambient environment.Ribs 154 and 156 of the seal function as a seal around the drive hub 34.This seal ensures that the suction drawn through the handpiece causesfluid flow from the distal end of the drive shaft 40, not thesurrounding environment. Stop tabs 150, in combination with therelatively large diameter of the drive hub head 176, cooperate toprevent the drive hub and drive shaft sub assembly from falling out ofthe outer hub and outer shell subassembly.

It should be recognized that the foregoing was a description of onepreferred version of the invention and that other versions of theinvention may vary from what has been described. For example, whilegenerally the surgical handpiece 20 and complementary cutting accessorythat form the system of this invention are designed to performendoscopic surgery, use of the invention is not so limited. Thecomponents of the system of this invention can also be employed toperform other types of surgical procedures.

Also, some versions of the invention may not include all features of thedescribed version of the invention. For example, some systems of thisinvention may not have the coils that are employed to facilitateinductive signal transfer between the handpiece and complementarycutting accessory. In some of these versions of the invention, it maytherefore not be necessary to provide the collet as a component separatefrom the handpiece housing. In these versions of the invention, thelocking ring, the wave spring and the cover plate are fitted directlyonto the handpiece housing or body. An advantage of this arrangement ofthe invention is that it even further reduces the number of componentsthat need to be provided in order to construct the handpiece of thisinvention.

Similarly, there may be reasons to provide a tool system of thisinvention with some or all of the features of the coil seal but not toemploy the specifically disclosed means for releasably holding the outerhub to the handpiece. Thus, an alternative version of the invention maycomprise an elastomeric member attached to the proximal end of the hubthat includes one or more of the described ribs. This version of theinvention may be constructed if the cutting accessory is not providedwith an RFID chip. In these versions of the invention, the ribs of thesemembers perform the sealing function of described ribs 154 and 156. Inthese versions of the invention, the outer hub is provided with surfacefeatures different from the described ears to facilitate the releasableattachment of the cutting accessory to the handpiece.

With regard to the ribs 154 and 156, it should similarly be recognizedthat their number are exemplary, not limiting. Some versions of theinvention may be provided with a single rib, some versions three or moreribs. Also, in the described version of the invention the rib 156 isseated is of smaller outer diameter than rib 154. This is because thesection of the inner wall of the housing against which rib 156 is ofsmaller diameter than the section against which rib 154 abuts. Inalternative versions of the invention, the diameters of these ribs mayvary to compensate for like differences in the profiles of the surfacesthe ribs are intended to abut.

Further, it should be recognized that the location of the coil seal locktabs 148 and the complementary outer hub openings in which the lock tabsare seated may be different from what has been described. Thus, the locktabs may be integral with the distal end section 140 of the seal. Also,both the end sections of the seal may, in some versions of theinvention, be provided with lock tabs. In these versions of theinvention it should be understood that the outer hub is formed withlongitudinally spaced openings in which the lock tabs are seated.

It should similarly be recognized that the geometry and number of thestop tabs 150 may vary from what has been described. For example, insome versions of the invention, instead of providing two tabs, the stopmember may be a ring formed of flexible material. The ring thus definesan open section of the outer hub base proximal end opening that has adiameter greater than that of drive hub neck 174 and less than that ofthe drive hub head 176. This ring may or may not be provided with slotsto facilitate its flexing in order to allow the insertion of the drivehub head into the outer hub proximal end opening. Alternatively, threeor more tabs formed of flexible, compressible or otherwise yieldingmaterial may be provided as stop tabs.

Also, the number of ears 135 integral with the cutting accessory outerhub 38 may be different from what has been described. In some versionsof the invention, it may be desirable to provide a single ear 135. Thisversion of the invention may be provided when there is a need toposition the cutting accessory in a specific rotational orientationrelative to the handpiece 20. In other versions of the invention, it maybe desirable to provide the cutting accessory with three or more ears.In these versions of the invention, the collet and locking ring areappropriately shaped to accommodate the seating of the ears that do notabut the lock ring. An advantage of these versions of the invention isthat they further reduce the extent to which the cutting accessory 22needs to be rotated in order to position one ear in the slot 86 wherethe locking ring will then block the movement of the ear.

Also, alternative constructions of the coupling assembly may bepossible. For example, in some versions of the invention, the wavespring and release button may be on opposite sides of the locking ring.In these versions of the invention, the lip portion of the locking ring,the portion that blocks movement of the outer hub 38 is located adjacentthe wave spring. The spring biases the locking ring so that the lip isnormally in the locked state. The release button is depressed to retractthe lip into an adjacent slot in the collet so as to place the lockingring in the release state.

Similarly, the biasing member that holds the locking ring in the lockedstate may have different forms than what has been described. Forexample, not all spring versions of this biasing member need be wavesprings. In some versions of the invention, a coil spring or leaf springmay perform this function. Also, this biasing member need not always bea metal or plastic spring. In alternative versions of the invention,elastomeric material disposed between a static component integral withthe handpiece housing and the locking ring may serve as the member thatreleasably holds the locking ring in the locked state.

It should likewise be understood that the geometry of the components ofthis invention may vary from what has been described. For example, thereis no requirement that the accessory outer hub and complementaryhandpiece opening in which the hub is inserted always have a circularprofile. In other versions of the invention, it may be desirable thatthese components have an oval profile or in the form of a polygon, forexample, a square or pentagonal shape. Similarly, the ears of the outerhub, which function as its lock tabs, may have a geometry different fromwhat has been described. For example, there may be a reason to providethe longitudinally extending surfaces of these components with linearprofiles.

Also, it should be recognized that not all versions of this inventionincorporate a motor as the power generating unit. In some versions ofthe invention, the power generating unit may consist of a device thatgenerates ultrasonic energy, RF energy, thermal energy or photonic,light, energy. In these versions of the invention, the coupling memberthat transfers the power generated by the power generating unit to thecutting accessory will be different from what has been described. Thecoupling member may also be different if the power generating unit isthe previously described motor 28. For example, sometimes the motoroutput shaft 30 may not be provided with a drive pin. In these versionsof the invention, teeth integral with the output shaft function as thecoupling member and engage with complementary teeth on the accessorydrive hub to transfer the motive power from the motor to the cuttingaccessory.

Therefore, it is an object of the appended claims to cover all suchvariations and modifications as come within the true spirit and scope ofthis invention.

1. A powered surgical handpiece comprising: a housing having a distalend defining a non-rotatable accessory coupling arrangement, said distalend having an accessory opening dimensioned to receive a proximal end ofa cutting accessory, a lock slot contiguous with the accessory openingdimensioned to receive a lock tab that extends outwardly from theproximal end of the cutting accessory, and a groove that intersects thelock slot and opens into the accessory opening; a power generating unitdisposed within said housing for actuating the cutting accessory, saidpower generating unit including a coupling member for transferring powergenerated by said power generating unit to the cutting accessory; a lockring fitted in the distal end of said housing so as to surround theaccessory opening and the lock slot, the groove accommodating a sectionof said lock ring that is disposed in the lock slot, wherein the grooveand the lock slot each have a depth, the depth of the groove beinggreater than the depth of the lock slot, said lock ring and said distalend of said housing collectively dimensioned so that when said lock ringis moved to the release state, said lock ring seats in a portion of thegroove below the lock slot; a release button integral with said lockring that is depressed to move said lock ring from the locked state to arelease state in which said lock ring is clear of the lock slot; abiasing member disposed between an outer surface of the distal end ofsaid housing and said lock ring or said release button so as to biassaid lock ring so that the release button is urged away from said distalend of said housing to hold said lock ring in a locked state wherein asection of said lock ring is disposed in the lock slot; and a coverplate fitted over said lock ring and secured to said distal end of saidhousing to hold said lock ring thereto.
 2. The powered surgicalhandpiece of claim 1, wherein said housing includes a body and a colletthat is attached to an end of said body to define the distal end of saidhousing.
 3. A powered surgical handpiece comprising: a housing having adistal end with an accessory opening dimensioned to receive a proximalend of a cutting accessory and a lock slot continguous with theaccessory opening dimensioned to receive a first lock tab that extendsoutwardly from the proximal end of the cutting accessory, said housingincluding an auxiliary slot separate from the lock slot that opens intothe accessory opening for receiving a second lock tab that extendsoutwardly from the proximal end of the cutting accessory; a powergenerating unit disposed within said housing for actuating the cuttingaccessory, said power generating unit including a coupling member fortransferring power generated by said power generating unit to thecutting accessory; a lock ring movably fitted in the distal end of saidhousing so as to surround the accessory opening and the lock slot; abiasing member disposed between said housing and said lock ring forholding said lock ring in a locked state wherein a section of said lockring is disposed in the lock slot; and a release button integral withsaid lock ring that is depressed to move said lock ring from the lockedstate to a release state in which said lock ring is clear of the lockslot.
 4. The powered surgical handpiece of claim 3, wherein said lockring is shaped to define an auxiliary indentation that at leastpartially subtends the area subtended by the auxiliary slot.
 5. Thepowered surgical handpiece of claim 3, wherein: said biasing memberextends between an outer surface of said housing and said lock ring orsaid release button so as to bias said lock ring so that the releasebutton is urged away from said housing; and a cover plate is fitted oversaid lock ring and secured to said housing to hold said lock ring tosaid housing.
 6. The powered surgical handpiece of claim 3, wherein:said housing includes a body and a collet that is attached to an end ofsaid body to form the distal end of said housing, said collet beingformed to define the accessory opening and the lock slot; and said lockring is movably secured to said collet and said biasing member extendsbetween said collet and said lock ring.
 7. The powered surgicalhandpiece of claim 3, wherein said power generating unit is a motor,said motor having an output shaft that extends into the opening and thecoupling member is integral with said output shaft.
 8. A poweredsurgical handpiece comprising: a housing having a distal end defining anon-rotatable accessory coupling arrangement, said distal end having anaccessory opening dimensioned to receive a proximal end of a cuttingaccessory and a lock slot contiguous with the accessory openingdimensioned to receive a lock tab that extends outwardly from theproximal end of the cutting accessory; a power generating unit disposedwithin said housing for actuating the cutting accessory, said powergenerating unit comprising a motor, said motor having an output shaftthat extends into the opening, and a coupling member integral with saidoutput shaft for transferring power generated by said power generatingunit to the cutting accessory; a lock ring fitted in the distal end ofsaid housing so as to surround the accessory opening and the lock slot;a biasing member disposed between the distal end of said housing andsaid lock ring for holding said lock ring in a locked state wherein asection of said lock ring is disposed in the lock slot; and a releasebutton integral with said lock ring that is depressed to move said lockring from the locked state to a release state in which said lock ring isclear of the lock slot.
 9. A powered surgical tool comprising: ahandpiece housing having a distal end and an accessory opening thatextends inwardly from the distal end and that is dimensioned to receivean outer hub of a cutting accessory; a collet attached to an end of saidhousing to form the distal end of said housing, said collet being formedto define a distal section of the accessory opening and a lock slot,said collet comprising: a base disposed in said housing, a head thatextends forward from said base and defines the distal end of saidhousing, and a skirt that extends from said head in surrounding relationwith said base and is spaced away therefrom so as to define an annularspace around said base; a coil disposed in said collet within theannular space defined by said base and said skirt of said housing; amotor disposed in said handpiece housing, said motor having a rotatingoutput shaft and a coupling member attached to said output shaft forreleasably coupling a drive hub of the cutting accessory to said outputshaft so that said output shaft and said drive hub rotate in unison; acoupling assembly attached to said handpiece housing for releasably andnon-rotably securing the outer hub of the cutting accessory to saidhandpiece housing, said coupling assembly comprising: the lock slotdefined in said collet extending longitudinally inwardly from the distalend of said housing and contiguous with the accessory opening, the lockslot being dimensioned to receive a lock tab that extends from an outersurface of the outer hub; a lock ring movably secured to said collet,said lock ring positioned to surround the accessory opening and the lockslot, said lock ring positioned to selectively intersect the lock slot;a biasing member extending between said collet and said lock ring forurging said lock ring into a locked state in which a section of saidlock ring intersects the lock slot; and a release button integral withsaid lock ring that is depressed to move said lock ring from the lockedstate to a release state wherein said lock ring is spaced from the lockslot.
 10. The powered surgical tool of claim 9, wherein: said handpiecehousing is formed with a groove that opens into the accessory opening,the groove being positioned to intersect the lock slot, wherein thegroove and the lock slot each have a depth, the depth of the groovebeing greater than the depth of the lock slot; and said lock ring andsaid handpiece housing are collectively dimensioned so that when saidlock ring is moved to the release state, said lock ring seats in aportion of the groove below the lock slot.
 11. The powered surgical toolof claim 9, wherein said coupling assembly is formed so that said lockslot and said release button are located opposite each other.
 12. Apowered surgical tool comprising: a handpiece having a distal end and anaccessory opening that extends inwardly from the distal end that isdimensioned to receive an outer hub of a cutting accessory; a motordisposed in said handpiece, said motor having a rotating output shaftand a coupling member attached to said output shaft for releasablycoupling a drive hub of the cutting accessory to said output shaft sothat said output shaft and said drive hub rotate in unison; a couplingassembly attached to said handpiece for releasably holding the outer hubof the cutting accessory to said handpiece, said coupling assemblycomprising: a lock slot defined in said handpiece that extendslongitudinally inwardly from the distal end thereof and that iscontiguous with the accessory opening, the lock slot being dimensionedto receive a first lock tab that extends from an outer surface of theouter hub; an auxiliary slot formed in said handpiece and being separatefrom the lock slot and opening into the accessory opening for receivinga second lock tab that extends outwardly from the outer hub of thecutting accessory; a lock ring mounted to said handpiece, said lock ringbeing positioned to surround the accessory opening and the lock slot,said lock ring being movably mounted to said handpiece and positioned toselectively intersect the lock slot, said lock ring being shaped todefine an auxiliary indentation that at least partially subtends thearea subtended by the auxiliary slot; a biasing member disposed betweensaid handpiece and said lock ring for urging said lock ring into alocked state in which a section of said lock ring intersects the lockslot; and a release button integral with said lock ring that isdepressed to move said lock ring from the locked state to a releasestate wherein said lock ring is spaced from the lock slot.
 13. Thepowered surgical tool of claim 12, wherein said coupling assembly isformed so that said lock slot and said release button are locatedopposite each other.
 14. The powered surgical tool of claim 12, wherein:said handpiece includes a housing and a collet that is attached to anend of said housing to form the distal end thereof, said collet beingformed to define a distal section of the accessory opening and the lockslot; and said lock ring is movably secured to said collet and saidbiasing member extends between said collet and said lock ring.
 15. Apowered surgical handpiece comprising: a housing having a distal endwith an accessory opening dimensioned to receive the proximal end of acutting accessory and a lock slot contiguous with the accessory openingdimensioned to receive a lock tab that extends outwardly from a proximalend of the cutting accessory; a power generating unit disposed withinsaid housing for actuating the cutting accessory, said power generatingunit including a coupling member for transferring power generated bysaid power generating unit to the cutting accessory; a lock ringdisposed in the distal end of said housing so as to surround theaccessory opening and the lock slot; a biasing member disposed betweensaid housing and said lock ring for holding said lock ring in a lockedstate wherein a section of said lock ring is disposed in the lock slot;and a release button connected to said lock ring that is depressed tomove said lock ring from the locked state to a release state in whichsaid lock ring is clear of the lock slot, said lock ring beingconfigured to receive and lock the cutting accessory to said housingwithout depressing of the release button.
 16. The powered surgicalhandpiece of claim 15, wherein said lock ring includes a lip having atapered face so that contact with a tapered face of the lock tab enablesmovement of the accessory to overcome the force of the biasing member toenable the handpiece to receive the cutting accessory without depressingof the release button.
 17. The powered surgical handpiece of claim 15,wherein: said handpiece is formed with a groove that opens into theaccessory opening, the groove intersecting the lock slot and beingpositioned to accommodate the section of said lock ring that is disposedin the lock slot, wherein the groove and the lock slot each have adepth, the depth of the groove being greater than the depth of the lockslot; and said lock ring and said handpiece are collectively dimensionedso that when said lock ring is moved to the release state, said lockring seats in a portion of the groove below the lock slot.
 18. Thepowered surgical handpiece of claim 15, wherein said handpiece isfurther formed to have an auxiliary slot separate from the lock slotthat opens into the accessory opening for receiving a second lock tabthat extends outwardly from the proximal end of the cutting accessory.19. The powered surgical handpiece of claim 15, wherein: said biasingmember extends between a surface of said housing and said lock ring orsaid release button so as to bias said lock ring and said housing sothat the release button is urged away from said housing; and a coverplate is fitted over said lock ring and secured to said housing to holdsaid lock ring to said housing.
 20. The powered surgical handpiece ofclaim 15, wherein: said housing includes a body and a collet that isattached to an end of said body to form the distal end of said housing,said collet being formed to define the accessory opening and the lockslot; and said lock ring is movably secured to said collet and saidbiasing member extends between said collet and said lock ring.
 21. Thepowered surgical handpiece of claim 15, wherein said power generatingunit is a motor, said motor having an output shaft that extends into theopening and the coupling member is integral with said output shaft. 22.A powered surgical handpiece comprising: a housing having a distal endwith an accessory opening dimensioned to receive the proximal end of acutting accessory and a lock slot contiguous with the accessory openingdimensioned to receive a first lock tab that extends outwardly from theproximal end of the cutting accessory; a power generating unit disposedwithin said housing for actuating the cutting accessory, said powergenerating unit including a coupling member for transferring powergenerated by said power generating unit to the cutting accessory; a lockring slidably fitted in the distal end of said housing so as to surroundthe accessory opening and the lock slot; a release button associatedwith said lock ring; and a biasing member disposed between an outer faceof said housing and said release button to hold said lock ring in alocked state wherein a section of said lock ring is disposed in the lockslot, wherein the release button is depressed to move said lock ringfrom the locked state to a release state in which said lock ring isclear of the lock slot.
 23. The powered surgical handpiece of claim 22,wherein: said handpiece is formed with a groove that opens into theaccessory opening, the groove intersecting the lock slot and beingpositioned to accommodate the section of said lock ring that is disposedin the lock slot, wherein the groove and the lock slot each have adepth, the depth of the groove being greater than the depth of the lockslot; and said lock ring and said handpiece are collectively dimensionedso that when said lock ring is moved to the release state, said lockring seats in a portion of the groove below the lock slot.
 24. Thepowered surgical handpiece of claim 22, wherein said handpiece isfurther formed to have an auxiliary slot separate from the lock slotthat opens into the accessory opening for receiving a second lock tabthat extends outwardly from the proximal end of the cutting accessory.25. The powered surgical handpiece of claim 22, wherein: said biasingmember urges the release button away from said housing; and a coverplate is fitted over said lock ring and secured to said housing to holdsaid lock ring to said housing.
 26. The powered surgical handpiece ofclaim 22, wherein: said housing includes a body and a collet that isattached to an end of said body to form the distal end of said housing,said collet being formed to define the accessory opening with the lockslot; and said lock ring is slidably secured to said collet and saidbiasing member extends between said collet and said lock ring.
 27. Thepowered surgical handpiece of claim 22, wherein said power generatingunit is a motor, said motor having an output shaft that extends into theopening and the coupling member is integral with said output shaft.